Field of the Invention
The present invention is related to a print data generating apparatus, a print data generating program, and a printing apparatus. Particularly, the present invention is related to an apparatus, a program, and a printing apparatus that generate print job data employed in face up paper discharge printing.
Description of the Related Art
Conventionally, when printing of image data generated by editing applications such as notepad and MS Word™ is performed, the image data are converted into PDL (Page Description Language) by a printer driver of a computer, then output to a printing apparatus.
PDL is a language that describes output images to printing apparatuses when printing text and images generated on a computer, to provide instructions to the printing apparatuses.
When printing text using printing apparatuses, it is necessary for data, such as data regarding positional information of letters and drawings, and data regarding fonts, to be converted into bit map data. PDL is the language that generates bit map images, and can describe the bit map images regardless of the type or resolution of the printing apparatuses.
Meanwhile, in ink jet printers, for example, ink jet heads are provided above printing sheets and a printing method in which ink is sprayed downward is commonly employed, in order to prevent contamination of portions of the printer by ink being transferred thereon immediately after printing.
Printed sheets which are printed by such ink jet printers are discharged onto paper trays with the printed surfaces facing upward, that is, discharged in a so called face up manner.
When face up paper discharge is performed, because the printed surfaces face upward, in the case that print job data generated by a printer driver includes a plurality of pages, it is necessary to start printing from the last page of the print job data in order to arrange the printed matter in correct page order.
However, when print job data described in PDL are printed, there are cases in which correct bit map data for printing cannot be obtained if expansion is performed from an intermediate portion of the print job data by utilizing page headers or the like.
Accordingly, it is necessary to sequentially perform expansion from the start of the print job data in order to positively generate correct bit map data for printing.
However, during face up paper discharge, it is necessary to output the last page of the print job data first, as described above. Therefore, conventionally, print job data were sequentially expanded from the start thereof, expanded bit map data were sequentially stored within apparatuses, output was stalled until an expansion process for a last page was completed, then printers performed printing of expanded bit map data from the last page to the first page when the expansion process for the last page was completed.
However, in such a method, printing of the first page becomes possible only after the expansion process for the last page is completed. Therefore, an extremely long amount of time is required before initiation of printing of the first page, and there is a drawback that processing times become long.
In addition, even if the processing capability of a processing apparatus that performs expansion processes is sufficiently greater than the physical printing speed of a printing apparatus, the standby time for the expansion processes will become longer as the number of pages of print job data to be processed increases. For example, in the case that the processing capability of a processing apparatus is 1,000 ppm (pages per minute) and the printing speed of a printing apparatus is 50 ppm, extraneous standby time for expansion processes will occur in the case that print job data have 20 or more pages.
Therefore, Japanese Unexamined Patent Publication No. H11(1999)-110171 proposes a method in which print job data are divided into a plurality of blocks, and processing is performed in reverse page order within each of the blocks.
In the method disclosed in Japanese Unexamined Patent Publication No. H11 (1999)-110171, standby time until a first page is printed is shortened because the print job data are divided into blocks. However, because printing is sequentially performed from blocks having smaller page numbers, in the case that a printing apparatus is equipped with only one paper tray, for example, blocks having smaller page numbers will be discharged first, then blocks having larger page numbers will be discharged on the earlier blocks. Therefore, although page orders will be correct in units of blocks, the page order will be incorrect for the printed matter as a whole.
Even if a printing apparatus is equipped with a plurality paper trays, and pages for each block are discharged onto each of the trays, users are still burdened with rearranging the printed matter discharged onto the trays after all sheets are discharged, for the printed matter as a whole to be in the correct page order.